This invention relates to electrochemical supercapacitors, and more particularly to a redox supercapacitor that is flexible so as to be able to take on a desired geometry.
The present invention commonly falls under the scientific classification of electrochemical supercapacitor. Electrochemical supercapacitors are commonly used as intermediate power sources in electric vehicle propulsion, backup computer battery systems, consumer electronics, etc., and can also be used for smaller, low-power devices.
Electrochemical supercapacitors are commonly classified into one of two energy storage mechanisms: double layer supercapacitors or redox supercapacitors. Double layer capacitors store energy by means of an electric double layer that forms on an electrode surface when subject to charging by the application of a potential difference between two electrodes separated by an electrolyte. Carbon materials (fiber matrices, nanotube sheets, paste/resin combinations, etc., which are faradaically inactive) are the most common electrode material for such supercapacitors. Because charge storage in double layer capacitors is a quantity related to the surface area, increasing the surface area is the primary goal to attain high energy densities.
Redox supercapacitors differ from electrochemical double layer capacitors in several regards. First, the mechanism of charge storage is not electrostatic (stored in an electrical double layer). Rather, charge is stored instead through the process of doping conducting polymer sheets within the redox supercapacitor during oxidation or reduction. An advantage of redox supercapacitors is that the amount of energy storage is a function of mass and not surface area. Increasing the mass of the conducting polymer materials will increase the amount of energy storage. In a system where volumetric dimensions are less critical than surface area dimension, redox supercapacitors may be advantageous.
It is an object of the present invention to provide a redox supercapacitor such that energy can be stored in a conformal, non-rigid configuration. As such, the redox supercapacitor of the invention can take on any desired geometry. The energy storage medium disclosed herein can be embedded into materials that change shape regularly such as clothing, accessories, robotic devices, etc.